Brachiopods
This plate of ink wash illustrations of brachiopods is typical of the illustration material prepared under the direction of Charles Doolittle Walcott, fourth Secretary of the Smithsonian Institution.. C.D. Walcott (1850-1927), was a geologist/paleontologist who specialized in the study of Paleozoic invertebrates. Walcott became the third Director of the United States Geological Survey in 1894. He held that position until 1907, when he became the fourth Secretary of the Smithsonian Institution. He remained Secretary until his death in 1927.

Walcott is especially well known for his work on Cambrian trilobites, and for discovering, collecting and describing the famous Cambrian fossils from the Burgess Shale in Canada.